We introduces RetroI2V, a novel infrastructure-to-vehicle (I2V) networking system that renovates conventional road signs to convey additional and dynamic information to vehicles. In particular, RetroI2V exploits the retroreflective coating of road signs and establishes visible light backscatter communication (VLBC), and further coordinates multiple concurrent VLBC sessions among road signs and approaching vehicles. RetroI2V features a suite of novel VLBC designs including late-polarization, complementary optical signaling and polarization-based differential reception which are crucial to avoid flickering and achieve long VLBC range, as well as a decentralized MAC protocol that resolves collisions and enables efficient multiple access in highly mobile and transient I2V settings. Experimental results from our prototyped system show that RetroI2V achieves more than 100 m of communication distance, supports many-to-many communications in typical road traffic pattern, and can provide sub-meter level ranging accuracy.
Purui Wang, Lilei Feng, Guojun Chen, Chenren Xu, Yue Wu, Kenuo Xu, Guobin Shen, Kuntai Du, Gang Huang, Xuanzhe Liu
ACM MobiCom 2020 [pdf]